Assessment of the Adequacy of Mucosal Oxygenation in Patients with Intraluminally Located Silicone Tonomitors
An indirect method for measuring the pH in the gastrointestinal mucosa has been applied to the monitoring and evaluation of patients who are critically ill. The method depends upon the knowledge that tissues are highly permeable to CO2 and that the PCO2 of fluid instilled into the lumen of a hollow organ will equilibrate with the PCO2 of tissue fluid and cells in the superficial layers of the wall of the hollow organ [1–4]. This is true for all parts of the gut including the stomach, for the PCO2 of fluid instilled into the lumen of this hollow organ rises and falls in parallel with changes in PC02 in arterial blood . The measurement of pH depends also upon the assumption that the [HCO3 −] in the wall of the organ is the same as that being belivered to it in arterial blood and upon the assumption that the pH in the tissue fluid is the same as that in plasma. The pH is calculated by substituting the measurements of PCO2 in luminal fluid and the [HCO3 −] in arterial blood in the Henderson-Hasselbalch equation.
KeywordsMultiple Organ Failure Ischemic Colitis Stress Ulceration Hollow Organ Chronic Mesenteric Ischemia
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